Uniaxial eccentric screw pump

ABSTRACT

A uniaxial eccentric screw pump includes: a casing  1;  a stator  2  having one end portion thereof connected to the casing  1  and having an inner peripheral surface formed into a female threaded shape; a rotor  3  configured to be insertable into the stator  2  and formed of a shaft body having a male threaded shape; and an end stud  4  connected to the other end portion of the stator  2.  The stator  2  is formed of: a stator body  10;  and an outer sleeve  9  detachably disposed on an outer peripheral portion of the stator body  10.  A closure structure which at least prevents intrusion of a foreign material from the outside is provided at a junction between the stator body  10  and the casing  1  and at a junction between the stator body  10  and the end stud  4.

CROSS REFERENCE TO RELATED APPLICATIONS

This is a National Stage application of International Application No. PCT/JP2014/082143, filed on Dec. 4, 2014, claiming priority to Japanese Patent Application No. 2014-013544 filed on Jan. 28, 2014, the disclosures of which are incorporated herein by reference in their entireties.

TECHNICAL FIELD

The present disclosure relates to a uniaxial eccentric screw pump.

BACKGROUND ART

Conventionally, as a uniaxial eccentric screw pump, there has been known a uniaxial eccentric screw pump having the configuration where a stator is formed of an outer sleeve and a stator body, and the stator is held between a casing and an end stud using stay bolts (see Japanese Unexamined Patent Application Publication No. 2011-256748, for example).

In such a conventional uniaxial eccentric screw pump, there may be a case where a high-temperature cleaning operation is performed such that an inner surface of the stator body is cleaned and sterilized simultaneously with the supply of a high-temperature fluid such as vapor or hot water into the stator body. In this case, the stator body expands. However, the deformation of the stator body toward the outer diameter side is obstructed by the outer sleeve and hence, a displacement amount toward the inner diameter side, that is, interference (overlapping between an outer surface of a rotor and an inner surface of the stator) is increased. When the rotor is rotated in such a state, a frictional force of the rotor against the stator body becomes excessively large and hence, there may be a case where an abnormal wear occurs on the stator body or the rotor is damaged. Further, there may be also a possibility that the rotor cannot be rotated.

On the other hand, to obviate such a state, the configuration may be considered where a larger gap is formed between an inner surface of a stator and an outer surface of a rotor so as to enable the rotation of the rotor even during a high-temperature cleaning operation. In such a case, however, a discharge pressure during a normal operation is decreased and hence, a desired discharge amount cannot be acquired.

SUMMARY Problems to Be Solved

It is an object of the present disclosure to provide an uniaxial eccentric screw pump which can convey a fluid material at a desired discharge pressure during a normal operation, the stator inside of which can be cleaned and sterilized at high temperature without generating abnormal wear on the stator, and can maintain an environment after cleaning by eliminating a possibility that the inside of the stator is exposed to ambient atmosphere and various germs or the like intrude into the stator.

Means For Solving The Problems

The present disclosure provides, as a means for solving the problems, a uniaxial eccentric screw pump which includes:

a casing;

a stator having one end portion thereof connected to the casing and having an inner peripheral surface thereof formed into a female threaded shape;

a rotor configured to be insertable into the stator and formed of a shaft body having a male threaded shape; and

an end stud connected to the other end portion of the stator, wherein

the stator is formed of: a stator body; and an outer sleeve detachably disposed on an outer peripheral portion of the stator body, and

a closure structure which at least prevents intrusion of a foreign material from the outside is provided at a junction between the stator body and the casing and at a junction between the stator body and the end stud.

With such a configuration, in the case where the inside of the stator body is cleaned and sterilized by a heated fluid, the outer sleeve can be removed from the stator body. Accordingly, even when a fluid of a high temperature is made to flow through the stator, the stator is expandable in the outer diameter direction and hence, it is possible to prevent the stator from being brought into pressure contact with the rotor due to the expansion of the stator toward the inner diameter side. Accordingly, also during a high-temperature cleaning, there is no possibility that a contact pressure between the rotor and the stator is increased so that interference becomes large more than necessary. Further, even during an operation where the outer sleeve is mounted or removed or even after the outer sleeve is removed, the intrusion of various germs or the like from the outside can be prevented by the closure structure and hence, an operation of the uniaxial eccentric screw pump can be changed over between a cleaning operation and a normal operation while an environment after cleaning is maintained.

It is preferable that the closure structure be a seal structure which prevents leakage of a fluid material toward the outside from both end portions of the stator.

With such a configuration, both during a normal operation and during a cleaning operation, air-tightness can be maintained. Accordingly, even when a fluid material to be conveyed is a chemical or the like, there is no possibility that the fluid material leaks to the surrounding of the uniaxial eccentric screw pump and contaminates the surrounding.

It is preferable that the stator body be made of rubber or a resin material, and the outer sleeve be made of a metal material.

With such a configuration, during a normal operation, the deformation of the stator body is suppressed by the outer sleeve made of a metal material so that proper interference can be maintained and hence, a discharge pressure at the time of conveying a fluid material by rotating the rotor can be set to a desired value.

It is preferable that the closure structure include: flange portions formed on connection portions of the end stud and the stator; a first clamp configured to hold both flange portions in a state where both flange portions are brought into contact with each other; flange portions formed on connection portions of the casing and the stator; and a second clamp configured to hold both flange portions in a state where both flange portions are brought into contact with each other.

With such a configuration, it is possible to easily acquire a closure state by only bringing end surfaces of the flange portions into contact with each other and by mounting the clamps on the flange portions. Further, the stator body can be easily exchanged by merely removing the clamps.

It is preferable that an adaptor made of a metal material be mounted on both end portions of the stator, and each adaptor form the flange portion.

With such a configuration, the flange portion can be easily formed on the stator having the complicated inner surface structure. Further, when it is necessary to exchange the stator due to wear, the adaptor can be reused by removing from the stator.

It is preferable that the uniaxial eccentric screw pump further include:

a stay bolt which connects the casing and the end stud to each other; and

a spacer which is mounted on the stay bolt from the outside, is brought into contact with the casing and the end stud respectively, and maintains the casing and the end stud with a fixed distance therebetween.

With such a configuration, even when the outer sleeve is removed, the distance between the casing and the end stud can be maintained at a fixed value by the spacer and hence, the stator body can be held at a desired compression state.

It is preferable that the outer sleeve be formed of a plurality of covers formed by splitting the outer sleeve in a circumferential direction, and the uniaxial eccentric screw pump include an adjusting unit configured to adjust a gap between the covers.

With such a configuration, it is possible to allow the stator body to expand in an outer diameter direction by only increasing the gap by the adjusting unit without disassembling the covers from the stator body.

It is preferable that the uniaxial eccentric screw pump include:

a detection unit configured to detect a degree of expansion of the stator body toward the outer diameter side; and

a control unit configured to automatically adjust the gap between the covers by performing a drive control of the adjusting unit based on a detection value from the detection unit.

With such a configuration, the gap between the covers can be automatically adjusted corresponding to the degree of expansion of the stator body in an outer diameter direction and hence, it is unnecessary for an operator to perform an adjusting operation by determining whether the operation is a normal operation or a cleaning/sterilization operation.

Effect Of The Disclosure

According to the present disclosure, in the case where the inside of the stator body is cleaned and sterilized by a heated fluid, the outer sleeve can be removed from the stator body and hence, even when the stator body is thermally expanded, the stator body can be deformed toward the outer diameter side whereby the rotation of the rotor is not obstructed. Accordingly, both during a normal operation and during a cleaning/sterilization operation, there is no possibility that the rotor is brought into pressure contact with the stator body and abnormal wear is generated. Further, the uniaxial eccentric screw pump includes the closure structure and hence, it is unnecessary to disassemble the stator body whereby an operation of the uniaxial eccentric screw pump can be changed over to a normal operation from a cleaning operation while an environment after cleaning is maintained.

BRIEF DESCRIPTION OF THE DRAWINGS

The foregoing and the other feature of the present disclosure will become apparent from the following description and drawings of an illustrative embodiment of the disclosure in which:

FIG. 1(a) is a schematic plan view of a uniaxial eccentric screw pump according to an embodiment, and FIG. 1(b) is a cross-sectional view taken along a line A-A in FIG. 1(a).

FIG. 2 is a schematic front view of the uniaxial eccentric screw pump shown in FIG. 1.

FIG. 3 is an enlarged cross-sectional view showing a state where a casing and a stator shown in FIG. 1(b) are in a disassembled state.

FIG. 4 is an enlarged cross-sectional view showing a state where the casing and the stator are connected to each other from the state shown in FIG. 3.

FIG. 5 is an enlarged cross-sectional view showing a state where the casing and the stator are fastened to each other by stay bolts from the state shown in FIG. 4.

FIG. 6 is a partially-enlarged view showing a state where the stator and an end stud shown in FIG. 1(b) are in a disassembled state.

FIG. 7 is an enlarged cross-sectional view showing a state where the stator and the end stud are connected to each other from the state shown in FIG. 6.

FIG. 8 is an enlarged cross-sectional view showing a state where the stator and the end stud are fastened to each other by stay bolts from the state shown in FIG. 7.

FIG. 9 is a schematic front view showing a clamp shown in FIG. 1.

FIG. 10(a) is a side view showing one end portion of a stator body according to another embodiment, and FIG. 10(b) is a cross-sectional front view showing a portion of one end portion of the stator body.

FIG. 11(a) is a schematic front view of a uniaxial eccentric screw pump according to another embodiment, FIG. 11 (b) is a side view showing a first support frame, and FIG. 11(c) is a side view showing a second support frame.

FIG. 12 is a schematic front view of a uniaxial eccentric screw pump according to another embodiment.

FIG. 13 is a schematic explanatory view showing a support structure of an outer sleeve according to another embodiment.

FIG. 14 is a schematic explanatory view showing a support structure of an outer sleeve according to another embodiment.

FIG. 15 is a schematic explanatory view showing an outer sleeve according to another embodiment.

MODE FOR CARRYING OUT THE DISCLOSURE

Hereinafter, embodiments according to the present disclosure are described with reference to attached drawings. In the description made hereinafter, terms indicating specific directions and positions (terms including “upper”, “lower”, “side”, and “end”, for example) are used when necessary. However, these terms are used for facilitating the understanding of the disclosure described with reference to the drawings, and the technical scope of the present disclosure is not limited by the meaning of these terms. Further, the description made hereinafter essentially only exemplifies examples of the present disclosure, and the description is not intended to limit the present disclosure, a product to which the present disclosure is applied, or the application of the present disclosure. Further, drawings are schematically shown, and the size ratios of respective parts and the like differ from those of actual parts.

FIG. 1 shows a uniaxial eccentric screw pump according to this embodiment. The uniaxial eccentric screw pump includes: a drive unit (not shown) disposed on one end side of a casing 1; a stator 2 disposed on the other end side of the casing 1; a rotor 3; and an end stud 4.

The casing 1 is a cylindrical body made of a metal material, and a coupling rod 5 is housed in the casing 1. One end portion of the coupling rod 5 is connected to a coupling 6, and power from the drive unit is transmitted to the coupling rod 5. A connecting pipe 7 is connected to an outer peripheral surface of the casing 1 on one end side, and a fluid material (for example, a food or the like having high viscosity such as margarine, soybean paste) can be supplied to the casing 1 from a tank or the like not shown in the drawing. Further, a flange portion 8 extending toward the outer diameter side is formed on an opening portion on the other end of the casing 1.

The stator 2 is formed of: an outer sleeve 9; and a stator body 10 disposed in a state where the stator body 10 is brought into close contact with an inner surface of the outer sleeve 9.

As shown in FIG. 2, the outer sleeve 9 is formed of an upper cover 27 and a lower cover 28 both of which are made of a metal material (for example, stainless steel or the like). The cover 27 is formed of a semicircular cylindrical portion 27 a and extending portions 27 b extending toward the outside from both side edge portions of the semicircular cylindrical portion 27 a, while the cover 28 is formed of a semicircular cylindrical portion 28 a and extending portions 28 b extending toward the outside from both side edge portions of the semicircular cylindrical portion 28 a. The outer sleeve 9 is formed such that the upper cover 27 and the lower cover 28 are fastened to each other by bolts 38 a and nuts 38 b by making use of through holes formed in the extending portions 27 b, 28 b in a state where the semicircular cylindrical portions 27 a, 28 a are disposed on upper and lower portions of an outer periphery of the stator 2 and the extending portions 27 b, 28 b opposedly face each other. With such a configuration, the extending portions 27 b, 28 b are brought into contact with each other, and the semicircular cylindrical portions 27 a, 28 a are brought into close contact with an outer peripheral surface of the stator 2. In performing a normal operation where a fluid material is conveyed by rotating the rotor 3 in such a state, the deformation of the stator body 10 is suppressed by the outer sleeve 9 made of a metal material so that proper interference can be maintained. Accordingly, a discharge pressure at the time of conveying the fluid material can be set to a desired value.

The stator body 10 is formed of a cylindrical body (for example, circular cylindrical body) made of an elastic material such as rubber or a resin which is selected as desired corresponding to a material to be conveyed (for example, silicon rubber, or a fluoro-rubber when the stator body 10 is used for cosmetics or the like containing silicon oil). An inner peripheral surface of a center hole of the stator 2 is formed into a single-stage or multi-stage female threaded shape of n-thread. On both end portions of the stator body 10, ring portions 11 a, 1 lb having a slightly large outer diameter size respectively are formed, and adaptors 12 a, 12 b are respectively mounted on the stator body 10 by making use of these ring portions 11 a, 11 b.

The adaptors 12 a, 12 b are made of a metal material such as stainless steel. As shown in FIG. 1, each adaptor 12 a, 12 b is formed of a cylindrical portion 13 a, 13 b and a flange portion 14 a, 14 b which projects toward the outer diameter side from one end of the cylindrical portion 13 a, 13 b. On each flange portion 14 a, 14 b, the first annular recessed portion 14 a 1, 14 b 1 and the second annular recessed portion 14 a 2, 14 b 2 which has an inner diameter size smaller than that of the first annular recessed portion 14 a 1, 14 b 1 are formed in this order from an end surface of the flange portion 14 a, 14 b. Since the stator body 10 is made of an elastic material, the adaptors 12 a, 12 b is mounted on the stator body 10 by elastically deforming the ring portions 11 a, 11 b toward the inner diameter side.

The adaptor 12 a is held by a first clamp 15 in a state where the flange portion 14 a is brought into contact with a flange portion 18 of the end stud 4 described later. As shown in FIG. 9, the first clamp 15 is formed of a pair of semicircular clamp portions 15 b, 15 c which is rotatably connected to a pivotally supporting portion 15 a. The first clamp 15 further includes a clip portion 15 d which fixes both clamp portions 15 b, 15 c so as to form an annular shape. Both clamp portions 15 b, 15 c hold the flange portion 14 a of the adaptor 12 a and the flange portion 18 of the end stud 4 by an annular groove (not shown) formed on inner peripheral surfaces of the clamp portions 15 b, 15 c in an annular shape. On the other hand, the adaptor 12 b is held by a second clamp 16 having substantially the same configuration as the first clamp 15 in a state where the flange portion 14 b of the adaptor 12 b is brought into contact with the flange portion 8 of the casing 1.

Both the first clamp 15 and the second clamp 16 are made of substantially the same metal material (in this embodiment, stainless steel) as the adaptors 12 a, 12 b. That is, the adaptors 12 a, 12 b and the first and second clamps 15, 16 which are made of substantially the same hard material can be brought into direct contact with each other. Accordingly, unlike the case where the stator body made of a resin, a rubber material or the like and the first clamp 15 or the second clamp 16 made of a metal material are brought into direct contact with each other, in this embodiment, there is no deformed portion and hence, a state where the adaptors 12 a, 12 b are held by the first and second clamps 15, 16, respectively, can be held in a stable manner. Therefore, the positional displacement of these portions at the junctions can be prevented. Accordingly, a pressure contact state of the stator body 10 which is made of soft rubber or a resin material with the flange portions 14 a, 14 b of the adaptors 12 a, 12 b, the flange portion 8 of the casing 1 and the flange portion 18 of the end stud 4 all of which are made of a hard metal material can be brought into a desired state. As a result, air-tightness of the respective junctions can be maintained and hence, both during a normal operation and during a cleaning operation, it is possible to prevent leakage of a liquid and intrusion of various germs brought about by the exposure of the junctions to ambient atmosphere.

As shown in FIG. 10, a metal-made ring 39 may be incorporated in the ring portions 11 a, 11 b formed on both end portions of the stator body 10 respectively (only a ring portion 11 a side shown in FIG. 10). With such a configuration, a clamping state acquired by the clamps 15, 16 can be further strengthened thus further enhancing air-tightness of the junctions. Further, in addition to the configuration where the metal-made ring 39 and the metal-made adaptors 12 a, 12 b are used in combination, by imparting a function of the adaptor 12 a or 12 b to the ring 39, at least either one of the adaptors 12 a or 12 b can be omitted.

As shown in FIG. 1, the rotor 3 is formed by forming a shaft body made of a metal material into a single-stage or multi-stage male threaded shape of n-1 thread. The rotor 3 is disposed in the inside of the center hole of the stator 2, and a conveyance space 17 continuously connected in a longitudinal direction of the center hole is formed. One end portion of the rotor 3 is connected to the coupling rod 5 on a casing side. The rotor 3 rotates in the stator 2 and, at the same time, revolves along the inner peripheral surface of the stator 2 by a drive force from the drive unit (not shown). That is, the rotor 3 eccentrically rotates in the center hole of the stator 2 and hence, the rotor 3 can convey a material in the conveyance space 17 in a longitudinal direction.

Hereinafter, the connection between the casing 1 and the stator 2 and the connection between the stator 2 and the end stud 4 are described in detail with reference to FIG. 3 to FIG. 8. In a state where the adaptors 12 a, 12 b are respectively mounted on both end portions of the stator body 10 which mounts the outer sleeve 9 on the outer peripheral portion thereof, as shown in FIG. 3 and FIG. 6, distal end portions of the ring portions 11 a, 11 b project from the flange portions 14 a, 14 b of the adaptors 12 a, 12 b. In such a state, the flange portion 8 of the casing 1 and the flange portion 18 of the end stud 4 are respectively brought into contact with end surfaces of the respective adaptors 12 a, 12 b. The ring portions 11 a, 11 b are positioned in the annular recessed portion 8 b of the flange portion 8 and the annular recessed portion 18 b of the flange portion 18 respectively. The annular projecting portion 8 a of the flange portion 8 and the annular projecting portion 18 a of the flange portion 18 are positioned in the first annular recessed portions 14 a 1, 14 b 1 of the flange portions 14 a, 14 b, respectively. Then, the ring portions 11 a, 11 b are press-fitted into the annular recessed portions 8 b, 18 b of the respective flange portions 8, 18 so that the ring portions 11 a, 11 b are elastically deformed, and portions of the elastic deformation brings about the displacement of the stator body 10 in the axial direction. Along with such displacement, as shown in FIG. 4 and FIG. 7, the outer sleeve 9 is separated from the adaptors 12 a, 12 b.

Subsequently, the first clamp 15 is mounted on the adaptor 12 a and the flange portion 18, and the second clamp 16 is mounted on the adaptor 12 b and the flange portion 8 respectively so as to strengthen the connection between the stator body 10 and the end stud 4 and the casing 1. Then, the nuts 22 are fastened to the stay bolt 19 so as to clamp the outer sleeve 9 between the casing 1 and the end stud 4 by way of the support members 20. With such an operation, as shown in FIG. 5 and FIG. 8, the stator body 10 is compressed in the axial direction. Therefore, the end surface of the ring portion 11 a is brought into pressure contact with an inner end surface of the annular recessed portion 18 b of the end stud 4. Further, the end surface of the ring portion 11 b is brought into pressure contact with an inner end surface of the annular recessed portion 8 b formed on the flange portion 8 of the casing 1. Accordingly, desired gas-tightness can be ensured at the junctions and hence, both during a normal operation and during a cleaning operation, it is possible to prevent leakage of a liquid and intrusion of various germs brought about by the exposure of the junctions to ambient atmosphere.

The end stud 4 is formed of a cylindrical body made of a metal material. The flange portion 18 which extends outward is formed on an opening portion of the end stud 4 at one end of the end stud 4. The flange portion 18 is held by the first clamp 15 in a state where the flange portion 18 is brought into contact with the flange portion 14 a of the adaptor 12 a as described previously.

The end stud 4 and the casing 1 are connected to each other by stay bolts 19. That is, support members 20 are formed on an outer peripheral surface of the end stud 4 and on an outer peripheral surface of the casing 1 respectively in a state where the support members 20 are disposed at two positions in point symmetry with respect to an axis. The stay bolts 19 are made to pass through the support members 20 of the end stud 4 and the casing 1 respectively in a state where a cylindrical spacer 21 made of a metal material (for example, stainless steel) is mounted on each stay bolt 19 from outside, and a nut 22 is threadedly engaged with one end portion of each stay bolt 19. In this case, when the nuts 22 are fastened in a state where the outer sleeve 9 is removed from the stator body 10, each spacer 21 is brought into contact with the support member 20 of the end stud 4 and the support member 20 of the casing 1. Accordingly, the further fastening of the nuts 22 is not possible and hence, the distance between the end stud 4 and the casing 1 is maintained at a fixed value. On the other hand, when the nuts 22 are fastened in a state where the outer sleeve 9 is mounted on the stator body 10, the outer sleeve 9 is brought into contact with the cylindrical portions 13 a, 13 b of the adaptors 12 a, 12 b which are respectively mounted on both end portions of the stator body 10 before each spacer 21 is brought into contact with the support members 20. Accordingly, the further fastening of the nuts 22 is not possible and hence, the distance between the end stud 4 and the casing 1 is maintained at a fixed value wider (by approximately 1 mm) than the distance maintained by the spacers 21.

Next, the manner of operation of the uniaxial eccentric screw pump having the above-mentioned configuration is described. To discharge a fluid material from the tank and the like, the drive unit not shown in the drawing is driven so as to rotate the rotor 3 by way of the coupling 6 and the coupling rod 5. Therefore, the conveyance space 17 formed by an inner peripheral surface of the stator 2 and an outer peripheral surface of the rotor 3 moves in a longitudinal direction of the stator 2 and the rotor 3. Accordingly, the fluid material discharged from the tank is sucked into the conveyance space 17, and is conveyed to the end stud 4. After the fluid material reaches the end stud 4, the fluid material is further conveyed to another place.

In the uniaxial eccentric screw pump, when the conveyance of a fluid material is stopped, the fluid material remains in the stator 2. When the fluid material is kept remaining in the stator 2, there may arise a hygienically undesired situation. Further, there may also arise the case where the remaining fluid material adheres to the inner surface of the stator 2. Accordingly, cleaning and sterilization of the inside of the stator 2 are required. In this embodiment, it is possible to perform CIP (Cleaning in Place) where automatic cleaning is performed safely with a simple operation without disassembling production facility and SIP (Sterilizing in Place) where sterilization of equipment and piping is performed without disassembling equipment and piping from a state that the uniaxial eccentric screw pump was manufactured. Such operations can be performed hygienically because there is no possibility that various germs and the like in ambient atmosphere intrude into the stator 2.

For example, in performing the SIP, the outer sleeve 9 is removed from an outer periphery of the stator 2. Then, water vapor or pressurized hot water (heated fluid) is supplied to the uniaxial eccentric screw pump, and the rotor 3 is rotated by driving the drive unit. Although the stator 2 expands due to heat at this stage of operation, the outer sleeve 9 is removed and hence, the stator 2 can expand toward the outer diameter side whereby the expansion of the stator 2 toward an inner surface side can be suppressed. Accordingly, the rotation of the rotor 3 is not obstructed. By moving the conveyance space 17 by rotating the rotor 3, the heated fluid is made to flow smoothly thus cleaning and sterilizing the inner surface of the stator 2.

After SIP is finished, the uniaxial eccentric screw pump is cooled with a lapse of time. When the stator body 10 returns to an original shape due to such cooling, the outer sleeve 9 is mounted on an outer peripheral portion of the stator body 10 and the conveyance of a fluid material to be transferred originally can be started again.

In this manner, according to the uniaxial eccentric screw pump according to this embodiment, the outer sleeve 9 is configured to be removed at the time of supplying a heated fluid to the uniaxial eccentric screw pump. This configuration allows the expansion of the stator body 10 toward the outer diameter side by the heated fluid. Accordingly, there is no possibility that the stator body 10 expands toward the inner diameter side and obstructs the rotation of the rotor 3 and hence, the inside of the stator 2 can be cleaned and sterilized by supplying the heated fluid to the inside of the stator 2. Further, both end portions of the stator body 10 always maintain a state where these end portions are connected to the end stud 4 and the casing 1 in an air-tight state and hence, there is no possibility that various germs or the like in ambient atmosphere intrude into the inner space of the stator 2 whereby the stator 2 can maintain a clean environment after sterilization.

Further, at the time of cleaning and sterilization, the stator body 10 can thermally expand toward the outer diameter side of the stator body 10 and hence, it is unnecessary to increase a gap between an inner surface of the stator and an outer surface of the rotor by taking into account of the thermal expansion of the stator body 10 toward the inner diameter side. Accordingly, in a normal operation state where the stator body 10 does not thermally expand, it is possible to set a contact pressure between the inner surface of the stator body 10 and the outer surface of the rotor 3 and interference (overlapping between the inner surface of the stator body 10 and the outer surface of the rotor 3) to appropriate values. Accordingly, it is possible to efficiently perform the conveyance of a fluid material during a normal operation such that a discharge pressure takes a desired value.

The present disclosure is not limited to the configuration described in the above-mentioned embodiment, and various modifications are conceivable.

For example, in this embodiment, the uniaxial eccentric screw pump is disposed in a lateral direction (horizontal direction). However, by arranging the uniaxial eccentric screw pump in a longitudinal direction (vertical direction), a fluid material may be conveyed downward.

In the above-mentioned embodiment, although the support structure for the uniaxial eccentric screw pump, particularly, the support structure for the stator 2 is not particularly mentioned, the following configuration can be adopted.

That is, as shown in FIG. 11, the end stud 4 and the casing 1 are supported by first support frames 23 fixed to a base respectively. The first support frame 23 is formed of a bottom surface portion 23 a, and both side surface portions 23 b, 23 c. A center portion of the bottom surface portion is fixed to the base by a bolt, and bolts are threadedly engaged with the end stud 4 and the casing 1 by way of both side surface portions. The stator 2 is supported by second support frames 24 fixed to the base. The second support frame 24 is formed of both side surface portions 24 a, 24 b and an upper surface portion 24 c which connects upper end portions of both side surface portions 24 a, 24 b to each other. Lower end portions of both side surface portions 24 a, 24 b are bent in horizontal direction and are fixed to the base by bolts. Further, a projecting portion 25 which is brought into contact with the outer sleeve 9 is integrally formed with an inner surface of one side surface portion. A wing screw 26 is threadedly engaged with the other side surface portion from an outer surface side, and a distal end portion of the wing screw 26 is brought into contact with the outer sleeve 9. By changing a threadedly engaging position of the wing screw 26, a pressing force of the distal end portion of the wing screw 26 to the outer sleeve 9 can be adjusted.

As shown in FIG. 12, an upper cover 27 and a lower cover 28 which form the outer sleeve 9 may be held by clamping members 29. The clamping members 29 includes an upper plate 30 and a lower plate 31 which are configured to clamp extending portions 27 b of the upper cover 27 and extending portions 28 b of the lower cover 28 in a state where the extending portions 27 b, 28 b vertically overlap with each other. A mounting plate 33 is integrally formed with the lower plates 31 by way of connecting rods 32. The mounting plate 33 is fixed to the base by bolts. Bolts 38 a are made to pass through the upper plates 30 and the lower plates 31 of the clamping members 29 in a state where the upper plates 30 and the lower plates 31 clamp the extending portions 27 b of the upper cover 27 and the extending portions 28 b of the lower cover 28 of the outer sleeve 9 therebetween, and nuts 38 b are threadedly engaged with the bolts 38 a. By fastening the nuts 38 b, the upper cover 27 and the lower cover 28 of the outer sleeve 9 can be firmly fixed to each other.

As shown in FIG. 13, the support structure of the outer sleeve may be configured such that lower surfaces of the extending portions 28 b of the lower cover 28 are supported by support bases 34, and a pressing portion 35 is pressed to upper surfaces of the extending portion 27 b of the upper cover 27. The pressing portion 35 is configured to be elevated and lowered by a hydraulic cylinder 36. With such a configuration, at the time of cleaning and sterilizing the inside of the stator body 10 by a heated fluid, by elevating the pressing portion 35 by driving the hydraulic cylinder 36, a holding state of the stator body 10 by the upper cover 27 is released. Therefore, even when a heated fluid is supplied to the inside of the stator body 10, it is possible to allow the stator body 10 to be deformed toward an outer diameter side due to thermal expansion. Accordingly, there is no possibility that an inner surface of the stator body 10 expands toward the inside and obstructs the rotation of the rotor 3. As a result, it is possible to convey a heated fluid by rotating the rotor 3 in the inside of the stator body 10. A drive unit for elevating and lowering the pressing portion 35 is not limited to the hydraulic cylinder 36, and various drive units such as a pneumatic cylinder, a solenoid and a motor can be adopted. By forming a through hole in the respective extending portions 27 b of the upper cover 27 and by allowing a guide shaft to pass through each through hole, it is possible to restrict a movable range of the pressing portion 35 in elevation.

As shown in FIG. 14, in place of the pressing portion 35, the upper cover 27 may be pressed to the lower cover 28 by displacing a gate-like guide member 37 which is driven by a hydraulic cylinder or the like not shown in the drawing downward.

Although not shown in the drawing, a distance between the upper cover 27 and the lower cover 28 may be adjusted. That is, threaded holes may be formed in the extending portions 27 b of the upper cover 27 and the extending portions 28 b of the lower cover 28 respectively, and double-end bolts which have threads formed in the opposite directions on both end sides may be threadedly engaged with the respective threaded holes. With such a configuration, the upper cover 27 and the lower cover 28 can be made to approach each other or to be separated from each other by rotating the double-end bolts.

In this case, the double-end bolts may be rotated by a drive unit such as a motor not shown in the drawings. In starting cleaning and sterilizing treatment of a uniaxial eccentric screw pump, it is preferable to widen the distance between the upper cover 27 and the lower cover 28 by rotating the double-end bolts by automatically driving the drive unit. This operation may be automatically performed, for example, based on a detection signal from a detector such as a temperature sensor which detects a temperature of the stator body 10 or a pressure sensor which detects a degree of expansion of the stator body 10. For example, a control device may perform a control such that a detection signal is fetched from the detector, and the distance between the upper cover 27 and the lower cover 28 is changed in a stepwise manner based on whether or not the detected value exceeds a predetermined value or the like. With such a configuration, without manpower, the distance between the upper cover 27 and the lower cover 28 can be automatically adjusted so as to prevent the stop of the rotation of the rotor 3 which may be caused by the expansion of the stator body 10 at the time of cleaning and sterilizing the uniaxial eccentric screw pump.

Although such automatic adjustment of the distance between the upper cover 27 and the lower cover 28 is performed using the double-end bolts, the automatic adjustment of the distance can be also performed using the bolts 38 a and the nuts 38 b shown in FIG. 2 and FIG. 12, for example. Further, it is possible to impart an automatic adjusting function to the configurations shown in FIG. 13 and FIG. 14 besides the above-mentioned configurations.

The outer sleeve 9 is not limited to the two-split structure consisting of the upper cover 27 and the lower cover 28. Provided that the outer sleeve 9 is formed of a plurality of covers formed by splitting the outer sleeve 9 in a circumferential direction, the number of splitting is not particularly limited. For example, FIG. 15(a) shows the outer sleeve 9 which is split in three in the circumferential direction, and FIG. 15(b) shows the outer sleeve 9 which is split in four in the circumferential direction.

DESCRIPTION OF SYMBOLS

-   1 Casing -   2 Stator -   3 Rotor -   4 End stud -   5 Coupling rod -   6 Coupling -   7 Connecting pipe -   8 Flange portion -   9 Outer sleeve -   10 Stator body -   11 a, 11 b Ring portion -   12 a, 12 b Adaptor -   13 a, 13 b Cylindrical portion -   14 a, 14 b Flange portion -   15 First clamp -   15 a Pivotally supporting portion -   15 b, 15 c Clamp portion -   15 d Clip portion -   16 Second clamp -   17 Conveyance space -   18 Flange portion -   19 Stay bolt -   20 Support member -   21 Spacer -   22 Nut -   23 First support frame -   24 a, 24 b Side surface portion -   24 c Upper surface portion -   24 Second support frame -   25 Projecting portion -   26 Wing screw -   27 Upper cover -   27 a Semicircular cylindrical portion -   27 b Extending portion -   28 Lower cover -   28 a Semicircular cylindrical portion -   28 b Extending portion -   29 Clamping member -   30 Upper plate -   31 Lower plate -   32 Connecting rod -   33 Mounting plate -   34 Support base -   35 Pressing portion -   36 Hydraulic cylinder -   37 Guide member -   38 a Bolt -   38 b Nut -   39 Ring 

1. A uniaxial eccentric screw pump comprising: a casing; a stator having one end portion thereof connected to the casing and having an inner peripheral surface formed into a female threaded shape; a rotor configured to be insertable into the stator and formed of a shaft body having a male threaded shape; and an end stud connected to a second end portion of the stator, wherein the stator is formed of: a stator body; and an outer sleeve detachably disposed on an outer peripheral portion of the stator body, and a closure structure which at least prevents intrusion of a foreign material from the outside is provided at a junctions between the stator body and the casing and at a junctions between the stator body and the end stud.
 2. The uniaxial eccentric screw pump according to claim 1, wherein the closure structure is a seal structure which is configured to prevent leakage of a fluid material to the outside from the one end portion and the second end portion of the stator.
 3. The uniaxial eccentric screw pump according to claim 1, wherein the stator body is made of rubber or a resin material, and the outer sleeve is made of a metal material.
 4. The uniaxial eccentric screw pump according to claim 1, wherein the closure structure includes: flange portions formed on connection portions of the end stud and the stator; a first clamp configured to hold the flange portions in a state where the flange portions are brought into contact with each other; second flange portions formed on connection portions of the casing and the stator; and a second clamp configured to hold the second flange portions in a state where the second flange portions are brought into contact with each other.
 5. The uniaxial eccentric screw pump according to claim 1, further comprising: a stay bolt which connects the casing and the end stud to each other; and a spacer, which is mounted on the stay bolt from the outside, which is brought into contact with the casing and the end stud, and maintains the casing and the end stud with a fixed distance therebetween.
 6. The uniaxial eccentric screw pump according to claim 1, wherein the outer sleeve is formed of a plurality of covers formed by splitting the outer sleeve in a circumferential direction, and the uniaxial eccentric screw pump includes an adjusting unit configured to adjust a gap between the covers.
 7. The uniaxial eccentric screw pump according to claim 6, further comprising: a detection unit configured to detect a degree of expansion of the stator body toward the outer diameter side; and a control unit configured to automatically adjust the gap between the covers by performing a drive control of the adjusting unit based on a detection value from the detection unit.
 8. The uniaxial eccentric screw pump according to claim 2, wherein the stator body is made of rubber or a resin material, and the outer sleeve is made of a metal material.
 9. The uniaxial eccentric screw pump according to claim 2, wherein the closure structure includes: flange portions formed on connection portions of the end stud and the stator; a first clamp configured to hold the flange portions in a state where the flange portions are brought into contact with each other; second flange portions formed on connection portions of the casing and the stator; and a second clamp configured to hold the second flange portions in a state where the second flange portions are brought into contact with each other.
 10. The uniaxial eccentric screw pump according to claim 3, wherein the closure structure includes: flange portions formed on connection portions of the end stud and the stator; a first clamp configured to hold the flange portions in a state where the flange portions are brought into contact with each other; second flange portions formed on connection portions of the casing and the stator; and a second clamp configured to hold the second flange portions in a state where the second flange portions are brought into contact with each other.
 11. The uniaxial eccentric screw pump according to claim 2, further comprising: a stay bolt which connects the casing and the end stud to each other; and a spacer, which is mounted on the stay bolt from the outside, which is brought into contact with the casing and the end stud, and maintains the casing and the end stud with a fixed distance therebetween.
 12. The uniaxial eccentric screw pump according to claim 3, further comprising: a stay bolt which connects the casing and the end stud to each other; and a spacer, which is mounted on the stay bolt from the outside, which is brought into contact with the casing and the end stud, and maintains the casing and the end stud with a fixed distance therebetween.
 13. The uniaxial eccentric screw pump according to claim 4, further comprising: a stay bolt which connects the casing and the end stud to each other; and a spacer, which is mounted on the stay bolt from the outside, which is brought into contact with the casing and the end stud, and maintains the casing and the end stud with a fixed distance therebetween.
 14. The uniaxial eccentric screw pump according to claim 2, wherein the outer sleeve is formed of a plurality of covers formed by splitting the outer sleeve in a circumferential direction, and the uniaxial eccentric screw pump includes an adjusting unit configured to adjust a gap between the covers.
 15. The uniaxial eccentric screw pump according to claim 3, wherein the outer sleeve is formed of a plurality of covers formed by splitting the outer sleeve in a circumferential direction, and the uniaxial eccentric screw pump includes an adjusting unit configured to adjust a gap between the covers.
 16. The uniaxial eccentric screw pump according to claim 4, wherein the outer sleeve is formed of a plurality of covers formed by splitting the outer sleeve in a circumferential direction, and the uniaxial eccentric screw pump includes an adjusting unit configured to adjust a gap between the covers.
 17. The uniaxial eccentric screw pump according to claim 5, wherein the outer sleeve is formed of a plurality of covers formed by splitting the outer sleeve in a circumferential direction, and the uniaxial eccentric screw pump includes an adjusting unit configured to adjust a gap between the covers. 